Roll-up tarp assemblies for covering truck cargo boxes having an open top are widely utilized in the trucking industry for transporting grain and other commodity products. For example, U.S. Pat. No. 4,505,512 (Schmeichel et al.) discloses a roll-up tarp apparatus for an open truck box or trailer. The roll-up tarp assembly includes a tarp made from a flexible material. The tarp is secured along one side to the open top of the truck box. The other side of the tarp is attached to a tubular member with a plurality of flexible straps. A crank apparatus connected to the tubular member by a U-joint and collar assembly is utilized to roll the tubular member transversely of the truck box opening so as to selectively cover the open top truck box with the tarp or uncover the open top truck box. A plurality of hooks are attached to the side of the truck box opposite of the side to which the tarp is fixedly secured. The hooks retain the tubular member when the tarp is covering the truck box. Other known roll-up tarp assemblies utilize a hand crank mechanism to control the movement of the tubular member, but the general trend is to utilize a motorized arm that is interconnected to the tubular member to minimize the work needed to open and close the truck box and to simplify that activity.
In motorized or motor driven roll-up tarp assemblies, a biasing member can be used to assist the motor in moving the tubular member in an unroll direction. Typically, a bungee cord is interconnected to a collar located on the tubular member and the bungee cord extends from the collar, around a corner of the truck box and along at least part of the length of the truck box where the second end of the bungee cord is attached. As the tarp rolls up on the tubular member or unrolls from the tubular member, front and rear arms guide the tubular member across the top of the truck box that frames the top opening and supports the tarp over the top opening of the truck box.
Other well known roll-up tarp assemblies include springs and other mechanisms to bias the arms in the unroll direction. See, for example, U.S. Pat. No. 7,188,887 (Schmeichel) and U.S. Pat. No. 7,195,304 (Schmeichel).
The present invention addresses limitations and problems associated with the related art.